Snubber device



W. CLAYTON SNUBBER DEVI CE 2 Sheets-Sheet l Filed June l, 1965 INVENTORWc'ZZzm UZag/mz April 1e, 196s W. CLAYTON SNUBBER DEVICE Filed June l,1965 PRESSURE (P5 2 Sheets-Sheet z;

VOLUME (m5/PLACEMENT c. c.)

INVENTOR ATTORNEYS United States Patent O 3,378,036 SNUBBER DEVitCEWilliam Clayton, Pasadena, Calif., assigner to Qlayton ll'ianufacturingCompany, lll Monte, Calif., a corporation oi California Filed .lune l,1965, Ser. No. 460,297 22 Claims. (Cl. 13S-3G) ABSTRACT GF THEDlSCLGSURT.

Snubber for damping rapid pump pulsations comprising upper and lowerhousing sections, each having a cylindrical side wall portion and aconvex end wall with a ring clamped between the sections and extendinginwardly beyond the side walls to provide an abutment for a vulcanizedrubber core. rEhe core has a shoulder engaging the abutment and an uppercylindrical portion extending through the abutment on one side thereofin spaced relation to the side wall of said upper housing section andinto engagement with the end wall of the upper housing section; and alower cylindrical portion on the other side of the abutment ofsubstantially the same diameter as the lower housing section. The lowerhousing section has an inlet for liquid, and the lower end of the coreis spaced from said inlet to provide a surge chamber.

This invention relates generally to snubbers, and more particularly to asnubber device designed to be connected in a fluid system to cushion ordampen rapid pump pulsations, or sudden surges, in the liquid beingpumped into the system.

More specifically, the invention relates to an improved snubber deviceincluding a housing and a uniquely shaped non-metallic core or body ofresilient material mounted in the housing so that a portion thereof isexposed to the pressure surges or pump pulsations in the pipeline orsystem with which the snubber housing is connected. The inventionutilizes the principle of vulcanized natural rubber being substantiallyincompressable and, therefore, subiect to how or displacement inresponse to the application of force thereto. Hence, the resilient coreor body is preferably made of natural rubber compounded to a preselectedShore hardness and designed to flow or deform when pressure surges orpulsations in the liquid act thereon, whereby the surges or pulsationsare absorbed or dampened by displacement of portions of the resilientbody and the possibility of damage to the system or any componentsconnected therewith, is averted.

The present snubber device is an improvement over prior devices designedfor similar purposes, but which include a spring-pressed diaphragm, orsimply a concavoconvex resilient disc designed to absorb pulsations byflattening out. The spring-pressed type of snubber, while generallysatisfactory, is comparatively expensive and the spring ultimately losesits initial resistance to compression. The concave-convex t pe ofsnubber body, while relatively inexpensive, has the disadvantage thatafter is has been in `use for some time, its elasticity becomes impairedand it has a tendency to buckle or snapover in the manner of a Spencerdisc. The present snubber device is much less expensive than thespringpressed type, and is not subject to the undesirablecharacteristics of the concave-convex disc snubber, and it longer-livedthan both.

The present snubber device is of general utility, although especiallywell adapted for use in a steam cleaner of the type disclosed, forexample, in Arant Patent No. 2,755,130, wherein a positive displacementpump operates continuously to pump liquid to a heating coil, the

ice

liquid being heated and discharged through a nozzle when the device isin use to perform a cleaning operation, or pumped and by-passed when thenozzle is shut off. The Arant patent discloses a spring-presseddiaphragm type of snubber over which the present snubber device is aneconomical and mechanical improvement.

Another feature of the present snubber device is that it lends itself toa wide operating range of pressures and volumetric displacementrequirements through the diiferent operating characteristics that can beachieved by making the resilient core or body of a predetermined Shorehardness. Thus, the housing can be of lixed design and resilient coresof different Shore hardness mounted therein to meet given installationrequirements for ideal results.

he principal object of the invention is to provide a snubber device fora fluid line or system designed to cushion or dampen rapid pressuresurges and pulsations in liquid being pumped into said line or system.

Another object is to provide a snubber device employing a core or bodyof resilient material mounted within a housing to cushion or dampenpressure surges in a liquid line to which the housing is connected, andwhich is constructed to withstand rapid and high pressure surges orpulsations of a positive displacement pump without damage or failure.

Still another object is to provide a resilient core for a snubber deviceof the type described, designed so that portions thereof can be axiallyand laterally deformed or displaced under pulse pressure and recovertheir original configuration when the pressure is relieved and not takea Substantial permanent set.

Another object is to provide a housing for a snubber device designed toreceive a resilient core member of a given Shore hardness to meet aparticular range of operating pressure conditions.

A still further object is to provide a snubber device which has fewparts, is economical and easy to manufacture, and has a long lifeexpectancy.

Ohter objects and many of the attendant advantages of the presentinvention will become readily apparent from the following detaileddescription, when taken in connection with the accompanying drawings,wherein:

FlG. l is a diagrammatic view of a liquid heating system incorporatingthe snubber device of the present invention;

FIG. 2 is a vertical sectional view, taken generally along the line 2-2of FIG. l, showing the upper and lower sections of the snubber housingand the retaining ring in cross-section, and the resilient body inelevation;

FiG. 3 is a horizontal sectional view through the upper housing section,taken along the line 3-3 of FIG, 2;

FlG. 4 is a view similar to FiG. 2, but with the resilient core shown incross-section and as it appears when an impulse or surge pressure isapplied thereto, causing it to flow or deforrn; and

PEG. 5 is a graph showing the displacement properties of three resilientcore members of different Shore hardness compared with thecharacteristics of a spring coil type of snubber.

Referring now to the drawings, an example of a iiuid system of the kindin which the present snubber device is utilized is schematically shownin FIG. l and comprises a pipe or conduit 2 connected at one end to theoutlet of a suitable positive displacement pump 4. The other end of thepipe 2 is connected to the inlet of a heating coil 6, which can be apart of a steam cleaner, steam generator, or other apparatus. Leadingfrom the pipe 2 is a branch conduit which is connected to one of thebranches of a 4-way fitting l0. The relief valve l2 and a blowdown valve14 are connected by suitable pipe nipples 13 and 15, respectively, totwo other of the branches of fitting 19. The

snubber device is generally identified by the numeral 18 and isconnected to the remaining branch of the fitting 10 by a pipe nipple 16.A discharge pipe 17 is connected to the outlet of the heating coil 6 andleads to a source of demand.

It will be understood that the heating coil 6 can be heated by anysuitable means (not shown).

The snubber device 18 includes a housing Ztl comprising upper and lowercup-like sections 24 and 22. The lower housing section 22 includes acylindrical side wall 26, which merges at its lower extremity into adome-shaped end wall 28 having a boss 30 formed centrally thereon andprovided with a threaded inlet opening 32 for receiving the upper end ofthe nipple 16. The upper end of the cylindrical side wall 26 merges intoan annular, horizontal ange 34 through a rounded portion 36.

The upper housing section 24 includes a cylindrical side wall 3S, whichterminates at its upper, or outer end in a dome-shaped end wall 40having an axial air vent port 42.

The lower end of the cylindrical side wall 38 has an annular horizontalflange 44 formed thereon, including a rounded portion 46 which mergesinto the cylindrical side wall 38. The flanges 34 and 44 have alignedopenings 48 and 50, respectively, extending therethrough.

Received within the housing 20 is a unitary core or body 52 molded fromresilient material, preferably vulcanized natural rubber. The resilientcore 52 includes a lower cylindrical body portion 54 of an externaldiameter substantially the same as the internal diameter of thecylindrical side wall 26 of the lower housing section 22. The

core 52 has an overall axial length substantially less than the axialdistance between the end walls 28 and 40 (FIG. 2). The lower cylindricalbody portion 54 terminates at its lower end in a partially spherical orconvex dome 56 that is spaced from the end wall 28 to form a surgechamber 57 for liquid. The dome 56 provides a large surface area onwhich the pressure of the liquid can act.

The resilient core 52 also has an upper generally cylindrical bodyportion 5S of a diameter substantially less than the internal diameterof the cylindrical side wall 38 of the upper housing section 24 withinwhich it is received. The cylindrical portion 58 terminates at its upperend in a partially spherical or convex dome 6?, which engages the innersurface of the end wall 40, the dome 6) and the end wall 46 havingcomplementary configurations when the resilient body 52 is in itsrelaxed, or undistorted, condition as shown in FIG. 2.

The cylindrical portions 58 and 54 of the core 52 are concentric andhave an annular horizontal shoulder 61 at their juncture, which mergesby a rounded portion 62 with the outer surface of the upper body portion58. A ridge 64 projects outwardly as an extension of the shoulder 61.The lower surface 66 of the ridge 64 merges into the outer surface ofthe lower cylindrical portion 54 and is rounded to correspond to thecurvature of the rounded portion 36 of the ange 34 and seats thereon.The top Surface 68 of the shoulder 61 is annular and flat to provideample bearing surface for a purpose explained below. The ridge 64preferably has an initial axial thickness such that when the lowersurface 66 thereof is seated on the rounded ange portion 36, the topsurface 68 will project slightly above the top surface 72 of the flange34.

A retainer ring 74 is received over the generally cylindrical upperportion 58 of the resilient core 52, and includes a horizontal annularportion 76, a short axial cylindrical portion 78, and a rounded portionS0 interconnecting the portions 76 and 78. The rounded portion 80 of thering 74 corresponds in shape to the rounded portion 62 of the core 52,and the portions 78 extends axially for a short distance along thegenerally cylindrical portion 58 of said core. The upper body portion 58may be made truly cylindrical, but is preferably formed with a slightinward taper from the rounded portion 62 to its dome end 6G, say abouttwo degrees. Such taper facilitates inserting the portion 58 through thering 74.

The ring 74 has an outer diameter corresponding to the outer diameter ofanges 34 and 44 of the housing sections 22 and 24, and is provided withopenings 82 aligned with the openings 48 and 56 in said flanges. Thering 74 is sandwiched between the flanges 34 and 44 and all three aresecured together by bolts 84 and nuts 86. Thus, the ridge 64 on theresilient core 52 is clamped between the ring 74. and the lower housingsection 22. When the bolts 84 and nuts 86 are tightened, the ridge 64will be compressed between the annular portion 76 of the ring 74 and therounded portion 36 of the frange 34, thereby forming an effective sealto prevent leakage of liquid from the damping chamber 57 in the housingsection 22 into the upper housing section 24.

The resilient body S2 has a cylindrical recess 88 extending thereintofrom the crest of the dome 60 to a point below the level of the ridge64. Tlhe recess 88 is formed by a heated element (not shown) employed tofacilitate curing of the rubber during molding. However, the recess 8Sserves the useful purpose of accommodating displacement-dow of the corematerial, as will appear hereinafter.

The convex dome configuration for the lower end face 56 of the resilientcore 52 provides a larger surface area upon -which fluid pressure canact than would a dat, end surface. Moreover, the dome-shaped end surface56 is not subject to a snapover effect, and hen'ce there is no problemof the return of the resilient body 52 to its original configurationafter a displacement-causing liquid pressure pulse applied thereto hassubsided.

`FIG. 2 illustrates the resilient core 52 in its initial, undistortedcondition. It Will be noted that the dome surface 60 is engaged with theinner surface of the end wall 4t? of the upper housing section 24. Whenliquid under pressure is forced into the system by the positivedisplacement pump 4, it will enter .the damping chamber '57 in the lowerhousing section 22 through the branch pipe 8 and pipe nipple 16 and willact upwardly upon the dome surface 56. The hydraulic presure exerted onthe dome 56 will produce compressive forces 4that cause the .material ofthe core 52 at its outer periphery to tend to expand laterally andtightly engage the inner surface of the side wall 26 of the .lowerhousing section 28, and also cause portions thereof -to be displacedaxially so that `the material is deformed in the manner shown in FIG. 4.Thus, it will be seen that the dome 56 is distorted upwardly to displaceportions of the core material through the opening in the retaining ring74, thereby cau-sing dow of said core material into the upper housingsection 24. -In other Words, the volume of the core material displacedfrom the lower housing section 22 results in a corresponding volume ofcore materia-l being displaced in the upper housing section 24.

The flanges 34, 44, ring 74, `and the ridge 64 cooperate to eectivelydivide the resilient body 52 into the portions 54 and 58, so that thelower body portion 54 is restrained by side wall 26 against lateraldisplacement but is free to distort axially under fluid pressure;whereas the upper .body portion 58 is restrained by the end wall 4t)against axial distortion but is free at its outer periphery to distortlaterally by expanding in the upper housing section 2-4. When the lowerbody portion 54 distorts, it will be seen that a change in the volume ofthe space between the dome S6 and the end wall 28 of the lower housingsection 22 vwill occur, this change in Ivolume Iis called thedisplacement Volume, and its value is related to the Value of the liquidpresure applied to the resilient ibody 52 and to `the resilientcharacteristics of said body. A corresponding decrease in volume iseffected in the unoccupied space in the upper housing section 24 by'lateral expansion of the upper tbody portion 58 and inward displacementthereof in the region of the recess 88, as illustrated in FIG. 4.

When pump pressure surges or pulsations occur in the pipeline 2 of FIG.l, the pressure will n'se and fall rythmically within the chamber -57 inthe lower housing section 22 of the snubber device 1'8. Such rise inpressure will cause the resilient body 52 to rapidly distort in themanner described above, thus increasing the volume of the availablespace in the chamber 57 in the lower housing section 22 between the endwall 28 and the dome 56. The increased volume thus resulting within thelower housing section 22 readily absorbs the pressure surges in the pipe22, and elects damping or cushioning thereof. During the intervalbetween the pressure surges or pulsations, the inherent resilience ofthe material of the body 52 will cause said body to return as nearly toits original condition as the back-pressure in pipe 2 will permit.

The displacement volume occuring in the lower housing section 22, as aresult of pulse pressure being applied to the dome 56, `depends upon theShore hardness of the resilient core or body S2. Thus, referring to FIG.5, it has been found that the curve resulting from the plotting ofdisplacement -volume in cubic centimeters (cc.) against applied liquidpressure in pounds per square inch (psi.) for a resi-lient core 52 madeof natural rubber is not a straight line, and furthermore, will varydepending upon the Shore hardness of the material. For example, thecurve A shows the volumetric displacement of the resilient core 52 incubic centimeters under various pressure conditions, when made ofnatural rubber with a Shore hardnes of 83. Curve B corresponds to thatof a similar core but having a lower Shore hardness of 76. Curve Ccorresponds to a similar core having a still lower Shore hardness of 60.

It will be apparent from a comparison of the curves A, B and C, that thevolumetric displacement of the core material un'der various pressureconditions increases as the h'ardness of the natural rubber isdecreased. Thus, for a pressure range of 50 to 450 p.s.i., thevolumetric displacement of the core 52 with a Shore hardness of 83(curve A) varied from about 13 to 64 cc.; the core with -a 76 Shorehardness (curve B) varied from about 20 to l100 cc.; and a core with a60 Shore hardness varied from about 22 to 142 cc. Thus, over the rangeof 6() to S3 Shore hardness, volumetric displacement under the pressurerange of 50 to 450 p.s.i. can be varied from a low of 13 to 22 cc. to ahigh of 64 to 142 cc.

The foregoing values were obtained by tests made with resilient cores 52having an overall axial leng'th of about 5.94 inches, a lower bodyportion 54 diameter and length of about 5 inches and 2.63 inches,respectively, and an upper body portion 58 diameter and length of about3.6 inches and 3.31 inches, respectively. rihe radius of the dome 56 was3.44 inches and that of the dome 66 was 3.06 inches. The recess 8S was3A of an inch in diameter and 3.83 inches deep. The maximum distancebetween the housing end walls 28 and 46 was 6.195 inches.

As an instance of comparison, curve D illustrates the characteristics ofa comparable spring-pressed diaphragm type snubber having a rate of16,000 to 19,000 pounds per inch of compression. It will be noted thatthe volumetric surge chamber displacement of such device is quite closeto that obtained with the resilient core of the present invention havinga Shore hardness of 76 (curve B).

FIG. 5 readily illustrates that the displacement volume desired forparticular operating pressure conditions can be obtained by selecting aresilient body 52 having the de sired Shore hardness. This feature ofthe invention makes it possible to readily adapt the snubber device 13to meet a wide range of operating conditions.

Obviously, many modifications and variations of the present inventionare possible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described andillustrated.

I claim:

1. A snubber device, comprising: a hollow housing having an inlet at oneend for connection with a pipe subject to pressure pulsations; and acore of resilient, displaceable material within said housing comprisinga portion having an end disposed adjacent said inlet and having an outerperiphery confined against lateral displacement by the inner surface ofsaid housing but being free to be displaced axially in response topressure pulsations, and comprising another portion having an endconfined against axial displacement and an outer periphery free to bedisplaced laterally in response to axial displacemet of saidrst-mentioned portion.

2. A snubber device, comprising: a housing having a generallycylindrical, hollow body closed at its opposite ends by end walls, oneof said end walls having means thereon for connecting said housing to auid line subject to pressure pulsations; a core of resilient,displaceable material disposed within said housing, and having an axiallength substantially less than the distance measured between said endwalls, and means disposed approximately medially of said housing bodysecuring said resilient core therein with one end of said resilient corein engagement with the other end wall of said housing, the portion ofsaid resilient core between said securing means and said other end wallbeing generally cylindrical and substantially smaller in diameter thanthe portion of said housing within which it is received and the portionof said core between said securing means and said other end wall of saidhousing being generally cylindrical and of substantially the samediameter as the portion of the housing in which it is received.

3. A snubber device as recited in claim 2, wherein the securing meansincludes an annular abutment carried by and projecting inwardly into thehousing and wherein the resilient core has a shoulder engaged with saidabutment.

4. A snubber device as recited in claim 2, wherein said other end wallof the housing has a vent port therein.

S. A snubber device as recited in claim 2, wherein the other end of theresilient core has a convex dome shape.

6. A snubber as recited in claim 2, wherein the core of resilientmaterial is natural rubber having a Shore hardness of about 60 to 83.

7. A snubber device, comprising: a housing having a cylindrical sidewall, and an upper end wall and a lower end wall at the oppositeextremities of said side wall; a core of resilient, displaceablematerial within said housing; and means in said housing at a pointapproximately medially of said side wall forming an abutment and beingprovided'with a central opening, said core having an upper body portionof reduced diameter extending through said opening and engaging saidupper end wall, said core having a shoulder engaging the lower side ofsaid abutment and having a lower body portion below said shoulder ofsubstantially the same diameter as the inside diameter of said housing,said lower end wall having an inlet opening to admit liquid subject topulsations into said housing to act on said lower body portion.

8. A snubber device as defined in claim 7, wherein a damping chamber isprovided in the housing between the lower end wall of said housing andthe adjacent end of the lower body portion.

9. A snubber device as dened in claim 7, wherein the upper body portionis slightly tapered in a direction toward the upper end Wall.

it). A snubber device, comprising: a housing having e upper and lowerhollow, aligned, generally cylindrical sections each closed at its outerend by an end wall; means securing said housing sections together attheir inner ends; means on the end wall ot' the lower housing sectionfor connecting the same with a fluid line subject to pressurepulsations; a core of resilient material disposed within said housing,and having an axial length substantially less than the axial distancebetween said end walls; means on said resilient core engageable bycooperating means carried by said housing for securing said resilientcore within said housing with one end of sad reslient core in engagementwith the end wall of said upper housing section, said resilient coreincluding an upper body portion received within and of substantiallysmaller diameter than said upper housing section.

11. A snubber device as recited in claim 10, wherein said means on saidresilient core comprises an annular ridge, and wherein the means forsecuring the housing sections together includes an annular ange on theinner end of each housing section, at least the flange on said lowerhousing section being merged therewith by a rounded portion, and whereinthe means carried by the housing for securing the resilient core is ,aretaining ring encircling the upper body portion of said core andextending in between the flanges of said housing sections, said ridgeextending to a point between said retaining ring and the rounded portionof the flange on the lower housing section and seating thereon.

12. A snubber device as recited in claim 10, wherein the retaining ringincludes a rounded, and a generally cylindrical portion on the innerperiphery thereof extending along the upper body portion for a minorportion of the length thereof.

13. A snubber device as recited in claim it?, wherein the outer end ofsaid lower body portion has a convex dome shape.

14. A snubber device as recited in claim 13, wherein the end wall of thelower housing section has a congur-ation corresponding to said outer endof the lower body portion, and is spaced therefrom to provide a dampingchamber.

15. A snubber device as recited in claim 10, wherein the end wall of theupper housing section and the outer end of the upper portion have convexdome-shaped configurations.

16. A snubber device as recited in claim 10, wherein the end wall of theupper housing section has a Vent port therein, and wherein the resilientcore has an axial recess therein aligned with said vent port.

17. A snubber device, comprising: an upper housing section and a lowerhousing section, each having a cylindrical side wall, a bottom wall atone end, and an outwardly extending flange lat the opposite end, saidhousing sections being arranged with their anged ends facing each other;an annular retainingring having a portion disposed between said flangesand having a central opening of smaller diameter than the insidediameter of the side wall of said upper housing section; means securingsaid anges and retaining ring together; a core of resilient,displaceable material having generally cylindrical upper and lower bodyportions of diierent diameter and a shoulder at the juncture of saidupper and lower body portions, said lower body portion being disposed insaid lower housing section and having an outside diameter substantiallyequal to that of the inside diameter of said side wall of said lowerhousing section, said upper body portion being disposed in said upperhousing section and having an outside diameter substantially smallerthan the inside diameter of said upper housing section and extendingthrough the opening in said retaining ring, said shoulder being engagedwith the lower side of said retaining ring and the end of said upperbody portion being engaged with the inner side of the wall of said upperhousing section, the end wall of said upper housing section having acentral opening for venting air from said upper housing section, the endwall of said lower housing section having an inlet opening forconnecting the same with a pipe subject to liquid pulsations, said lowerbody portion having its lower end spaced from the end wall of said lowerhousing section to provide a damping chamber communicating with saidinlet opening.

18. For use in a snubber device of the character described, an integralbody of resilient, displaceable material, comprising: a rst generallycylindrical body p0rtion terminating in an end face having a convex domeshape; a second generally cylindrical body portion extending from and ofsubstantially smaller diameter than said rst body portion; an annularshoulder at the juncture of said rst and second body portions; and aridge projecting outwardly from said first body |portion at said vshoulder.

19. An integral resilient body as recited in claim 18, wherein both bodyportions terminate in an end face having a convex dome shape.

20. An integral resilient body as recited in claim 19, wherein said bodyis molded from natural rubber and has a Shore hardness in the range of60 to 83.

21. An integral resilient body, as recited in claim 18, wherein thefirst generally cylindrical body portion has a recess extending inwardlyfrom its convex end face.

22. An integral resilient body, as recited in claim 21, wherein therecess extends to a depth approximately in the plane ofthe ridge.

References Cited UNITED STATES PATENTS 2,300,722 11/1942 Adams et al.138-30 2,755,820 7/ 1956 Taylor 138-26 FOREIGN PATENTS 104,257 6/1938Great Britain.

LAVERNE D. GEIGER, Primary Examiner.

B. E. KILE, Assistant Examiner.

